[Coda]

This is normal behavior and almost every forum system will do this. Any other behavior would be a security risk.

The solution is to mark the "Remember Me" box so that you don't get automatically logged out.

Additionally, many people choose to write large posts in an external editor (Notepad or Wordpad for example) and paste them in so that problems with the web browser (including getting logged out, network interruptions, or the browser just doing something stupid like going back a page when you hit backspace). This is a more foolproof solution and will even endure problems like crashes because you can save to disk periodically as you work.

I apologize for the trouble, and I hope these recommendations can help you in the future.